"It is," Childermass agrees, only it also means he can pick not sticking around, too.

It may mark him as an utter spoilsport, but it'll be more comfortable for all three of them in the long run. Lambert and Strange can get drunk without their various Portland problems regarding the shadowy man looming over their poor coping methods and he, well, he just gets to go... do whatever, he supposes. Go drink alone in the cookhouse or something like that, but it's not as though he's unused to his nights ending like that from time to time.

So after one last look between the other two, he makes up his mind to just shake his head and say, "Which means I'm choosing to leave you to your fun without me. Try not to drink yourselves blind, gentlemen."

That means he's turning to cross back over to the door.